The present invention relates to fire suppression nozzles in a fire suppression system, and more particularly to an atomizing nozzle for a clean agent fire suppression system.
A “clean agent” system is one of a variety of commercially available fire suppression systems. The term “clean agent” denotes a system that utilizes suppressants which do not leave any residue in the fire zone after discharge. This type of system is ideal for sensitive electronics and/or documents. A typical clean agent system operates by pumping a gas suppressant (such as an inert gas) or a liquid/liquefied gas suppressant agent into the fire zone to inhibit the combustion process of a fire. The gas suppressant suppresses the fire by lowering the level of oxygen in the atmosphere of the fire zone. The reduction in oxygen inhibits combustion and starves the fire. Alternatively, or in addition to starving the fire, the liquid or the vaporizing liquefied-gas suppressant agent may chemically inhibit the combustion process.
Many types of clean agent systems using a variety of suppressants are commercially available. In one particular system, a suppressant agent is liquefied when stored under pressure in a container but is vaporized when released from the container. The suppressant agent is forced from the storage container by an inert gas propellant. The liquefied agent and propellant may form a two phase mixture (gas propellant, gaseous chemical agent, plus liquid chemical agent) in the pipe network of the fire suppression system. This mixture flows through the pipe network until it is discharged through an array of dual fluid nozzles into the fire zone. After discharge into the fire zone, the remainder of the liquefied suppressant agent is vaporized leaving no residue upon evaporation. The vaporized suppressant agent inhibits combustion by carrying heat away from the fire and breaking down the chemical structure of the fire.
In another clean agent system, a liquid suppressant (for example water) or a liquefied-gas suppressant agent is utilized. The liquid or liquefied gas agent is forced through the pipe network of the fire suppression system by a propellant. The propellant and suppressant agent mixture is further combined with additional quantities of a gas (for example an inert gas or Argonite™) in the pipe network of the fire suppression system to provide for total flooding of the fire zone. The mixture of liquid or liquefied gas suppressant, propellant, and gas flows through the pipe network until it is discharged through an array of dual flow nozzles into the fire zone. The suppressant and gas inhibit combustion by absorbing heat and by reducing the amount of oxygen in the atmosphere of the fire zone.
Dual fluid nozzles for clean agent systems such as the nozzle disclosed in United States Patent Application 2005/0001065A1 to Senecal have an internal choke point at or adjacent the nozzle's inlet. Choking the fluid flow internally can allow small droplets formed by the turbulence induced at the choke point to be dissipated when the fluid reforms into a flow sheet prior to discharge from the nozzle. As a result of the reformation of the fluid flow into the flow sheet prior to discharge, the liquid or liquefied suppressant droplets produced by the nozzle have sizes greater than about 20 micrometers (0.79 mils) in diameter upon discharge from the nozzle's outlet. These droplets do not precisely follow the typical conical or radial discharge flow path of the gas suppressant or propellant from the conventional nozzles due to their large momentum. Thus, some of the droplets tend to splash on and adhere to surfaces, such as the walls or the ceiling of the fire zone. Additionally, physical obstacles (such as partitions, desks, tables, or baffles) in the fire zone may obstruct the flow of the droplets, as the droplets may not be able to follow the path of the gas flow around these obstacles. The inability of some of the droplets to flow around obstacles may reduce or eliminate the ability of the fire suppression system to totally flood the fire zone. The result of the wet mist droplets' adherence to surfaces (and the droplets' reduced ability to circulate around obstacles) is that more suppressant agent is required for effective fire suppression, increasing the cost of the clean agent system.